Regulator for electric-heating systems



W. HARTWIG,

REGULATOR FOR ELECTRIC HEATING SYSTEMS.

APPLICATION FILED MAR- 25. 1918.

1,365,782. Patented Jan. 18, 1921.

UNITED STATES PATENT OFFICE.

WILLIAM HARTWIG, OF CHICAGO, ILLINOIS, ASSIGNOR TjO RAILWAY UTILITY COMPANY, OF CHICAGO, ILLINOIS, A CORPORATION OF ILLINOIS.

REGULATOR FOR ELECTRIC-IIEATING SYSTEMS.

Specification of Letters Patent. Patented Jan. 18, 1921.

Application filed March 25, 1918. Serial No. 224,435.

maintain the temperature of the car be-- tween certain limits by means of thermostatic control. My invention relates to the means for controlling'the heating system and has for its object to provide a simpler and less expensive system which is less liable to get out of operative condition, and consumes a minimum-amount of current in the regulation. f r

In the accompanying drawings I have illustrated diagrammatically a preferred embodiment of my invention. It is to be understood, however, that the specific disclosure is for the purpose of exemplification.

only, and that the scope of the invention is defined in the following claims in which I have endeavoredto distinguish it from the prior art so far as known to me, without, however, relinquishing or abandoning any portion or feature thereof.

.=..;Referring now to the drawing the source of current is represented diagrammatically byline 1, the trolley for taking current to the particular car at 2 the heater 5 and the contactor for controlling the current at 3. When the contactor 3 is closed the heating vcurrent trav'elsfrom line-1 through the trolley 2, armature 15, 'conta'cts 3, and blowout coil 4 to the heaters and thence to ground at 6 the course of the heating circuit being shown in heavy lines. The armature 15 and contacts '3 are controlled by the magnet 7 of the contactor-and the latter receives its cur rent for maintaining the contacts closed when the temperature is below that desired through the following circuit-line 1, trolley 2, wire 8, the coil-of magnet 7, wire 9, re-

' lay contacts 10, wire l1, resistance 12, -re

sistanc'e 13, and to ground at 14. Resistance 13, is preferably of about 4000 ohms sothat the-f current flowing through this controlling circuit is relatively very small, indeed.

The purpose of resistance 12 will presently appear.

he relay switch '10 is controlled by a magnet 16 of very fine winding and which' is inserted in a shunt about the magnet 7, relay contacts 10 and resistance 12, from the trolley 2, by wire 3 to the coil of magnet 16, thence by wire 17 to a thermometerthermostat 18, and when the thermostat closes the circuit by wire 19 to resistance 13.

strument well known in this art and need not be here described. When, however, the temperature attains the desired degree the column of mercury in the thermometerthermostat closes the circuit and the relay coil 16 is thereby energized. This causes the magnet to attract its armature 20 which in rising trips the arm 21 of the bell crank switch member 22. As the armature 20 rises and first comes into contact with the arm 21 it closes a shunt as follows,from

coil 13 through coil 12, wire 11, arm 21,

armature 20 and wire 3*. The resistance 12 is'so chosen, in practice about 50 ohms has been found to work satisfactorily, that when this circuit is closed the current through the thermometer-thermostat is greatly reduced but remains of sufiicient volume to cause the coil 16 to retain the. armature which has previously been raised. After the circuit just described has been closed the further movement of the armature 20 operating on the arm 21 opens the contacts 10 and deenergizes magnet 7 by which the heating circuit is. maintained closed.

Thereupon the heating circuit opens and.

remains open until the temperature again falls below that required. Then this happens the circuit is of'coursebroken through the thermometer-thermostat, the relay coil 16 denergized, dropping its armature, opening the circuit at the contact between said armature and arm 21, closing the con tact 10,-and again energizing coil 7 to attract its armature 15 and close the contacts of the heating circuit. When the temperature again rises to the required point the operation is repeated.

It will thus be seen that the circuit through the thermometer-thermostat, which is a somewhat delicate instrument and incapable of withstanding high electrical v w IVhen the temperature is below that I desired the circuit just described is open at 'the thermometenthermostat which is an inpressures, closes the circuit through the relay, it does so with the shunt comprising mometer-thermostat is avoided. It will also.

be observed that in my improved system the coils 7 and 16 are or may be grounded so that there is no necessity'for expensive installation of the comer of the coils.

I claim: t

1. In a deviceof the class described, a grounded electric heater, a connection from a source of electric energy to said heater, a pair of contacts interposed in and controlling said connection, an electro-magnetic device for maintaining the contacts closed including a coil connected to said source of electric energy and to ground, a relay switch, a larger and a lesser resistance in the connections of said coil to ground, a relay coil controlling said switch and a thermostat in shunt to said lesser resistance and switch.

2. In a device of the class described, a grounded electric heater, a connection from said heater to a source of electric energy, a contactor in said connection, a coil controlling said contactor, a relay switch, a connection from said relay switch to said coil, a small resistance connected to the relay switch, a larger resistance connected to the first said resistance, a connection from the larger resistance to ground, a shunt about said small resistance, and a switch comprising a thermostat and a coil, an armature electrically connected to and controlled by said coil and adapted when attracted thereby to engage and open said switch and also to shunt said thermostat.

WILLIAM G. HARTWIG. 

